Subject: [Stackevo] Class E

From: "Martin Thomson" <[email-masked]>
Date: Wed, 27 Mar 2019 09:08:41 -0400

I did some digging which lead to the earliest mention of class E that I could find in RFC 990.  It simply reserves class E for future use.

Is there a better reference for this?

---

From: Dave Thaler <[email-masked]>
Date: Wed, 27 Mar 2019 15:20:37 +0000

RFC 988 (Host Extensions for IP Multicasting) section 4:
   Host groups are identified by class D IP addresses, i.e. those with
   "1110" as their high-order four bits.  The remaining 28 bits are
   unstructured as far as hosts are concerned.  The addresses of
   well-known, permanent groups are to be published in "Assigned
   Numbers". Class E IP addresses, i.e. those with "1111" as their
   high-order four bits, are reserved for future addressing modes.

So there's unicast, multicast, and broadcast addressing modes.
Class E is reserved for "future addressing modes", meaning "none of the above".
Indeed there have been discussions about other addressing modes (anycast, 
xcast, incast, etc.).

Dave

-----Original Message-----
From: Stackevo <[email-masked]> On Behalf Of Martin Thomson
Sent: Wednesday, March 27, 2019 2:09 PM
To: Stackevo <[email-masked]>
Subject: [Stackevo] Class E

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